At times in the scientific-based art works of Jody Rasch and Betsy Stewart, it’s hard to grasp a sense of scale. Does a painting depict microscopic organisms, or distant arrays of stars? Is another painting a snapshot of galaxies, or a radar map of a hurricane? Does a third piece feature a fiery depiction of the sun, or a floating cell from an organism? Such tensions suffuse this American Association for the Advancement of Science dual show featuring works by New York-based Rasch, and Stewart, who works out of D.C. Stewart is known for her “pond totems” that depict the layers of organisms that inhabit shallow regions of water, perhaps most notably in this exhibition using a scroll. But some of Rasch’s works steal the show as they display his nimble and exhaustive penmanship. Like the seemingly endless hand-drawn lines of Linn Meyers, Rasch traces out mesmerizing expanses of curlicues in colored pencil—and they are as convincing and appealing up close as they are far away. The exhibition is on view to Feb. 1 at the AAAS Headquarters Art Gallery, 1200 New York Ave. NW. Free. (202) 326-6400. aaas.org. (Louis Jacobson)